The first widespread frost of the season is expected to hit the UK on Monday morning as overnight temperatures plummet to lows of minus 4C (25F).
While much of the country has enjoyed a comparatively balmy October so far, a blisteringly cold Sunday night will see temperatures fall below freezing in places.
Many people will wake up to frost on the ground on Monday morning.
Temperatures in Scotland will drop to lows of around minus 3C (27F) on Sunday night but Met Office forecaster Greg Dewhurst has warned that in some places it could dip as low as minus 4C (25F).
He said it was "the first widespread frost in the UK this autumn" and predicted the UK "could be seeing the coldest night" of the season so far.
Temperatures in London and the south of England will remain in single digits on Sunday night.
Despite some sunny spells during the day on Sunday, cooler air is expected to move in before temperatures fall.
Scotland will be looking at lows of 8C (46F) throughout Sunday and the south of England is expected to hold on to warmer temperatures of 14C (57F) to 15C (59F) before the drop later in the night.
Sky News weather producer Chris England said: "Clear skies and light winds overnight Sunday into Monday will allow temperatures to drop rapidly, giving an extensive frost by morning. Some mist and fog are likely too.
"We haven't had much in the way of frost yet this autumn, but it's certainly not unusual for the end of October. Increasing cloud on Monday night will keep it frost free, so it's really a one off."